Ralph Hasenhuttl praised teenage goalscorers William Smallbone and Jake Vokins after they fired Southampton into the fourth round of the FA Cup in a 2-0 victory over Huddersfield.

Making his first senior appearance, 19-year-old Smallbone gave the hosts the lead in the 48th minute with a well-timed volley.

Smallbone had only featured once for the Under-21s this season – in a Football League Trophy defeat to Forest Green in September – but had been named on the bench for Saints' New Year's Day draw with Crystal Palace.

Saints' progress was sealed in the 86th minute when Vokins, also 19, fired in from the edge of the area for his first senior goal.

"Will showed that on the ball he has some good moves, quality and fine touch," Hasenhuttl said about Smallbone.

The Austrian issued caution over the youngster's potential impact, adding: "In the end, he had some problems with his body.

"He was out for a long time with a calf injury and at the end he cramped up a little bit, so he must get fitter and stronger.

"On the ball he is one of the best lads in the academy, but football is also about winning the ball back."

Vokins was only making his second senior appearance for the club, and Hasenhuttl said: "Jake showed exactly what I know from him. He has some good moves and is very forward orientated.

"I think the reverse gear takes longer. It is up to us to work with him and make him better."

Huddersfield manager Danny Cowley admitted his squad had struggled with five matches in 14 days.

He said: "I thought it was a bit of a game of chess. We were pleased with our performance. I think we defended with a lot more intensity, more discipline and concentration than we did on New Year's Day for sure.

"We came here respecting Southampton and the fact that they've had a great Christmas, taking 10 out of 12 points, the athleticism they have at the top end of the pitch and how good they are at getting in behind you.

"We knew that as a consequence we had to protect that space so we defended deeper than we would normally, but we were pleased with the discipline and the concentration of the group."